The present invention relates to a polishing machine comprising a turntable having a polishing surface for polishing a semiconductor wafer or the like, and a polishing liquid supply unit for supplying a polishing liquid onto the polishing surface of the turntable.
In a semiconductor wafer manufacturing process, a polishing machine is used to planarize semiconductor wafer surfaces.
The polishing machine of the this kind comprises a turntable having a polishing surface and adapted to be turned at a predetermined rotating speed, a wafer carrier that holds a semiconductor wafer rotates at a predetermined rotating speed and presses a surface of the semiconductor wafer against the polishing surface of the turntable onto which a polishing liquid is being supplied so as to polish the surface of the semiconductor wafer, a dressing tool that is brought into contact with the polishing surface of the turntable while supplying a dressing liquid onto the polishing surface of the turntable to dress the polishing surface, and an airtight housing containing the turntable, the wafer carrier and the dressing tool therein.
As shown in FIG. 1, in a conventional polishing machine, a polishing surface of a turntable 201, which polishing surface is usually formed by attaching a polishing pad 202 to the upper surface of the turntable 201, is supplied with various kinds of liquids, including a polishing liquid and a dressing liquid which are needed for performing certain operations such as polishing of semiconductor wafers, dressing of the polishing surface and so on, through a nozzle 203 which is set above the turntable and connected to a liquid supply tube 205.
However, this conventional polishing machine has the following problems.
(1) The nozzle 203 and the liquid supply tube 205, which are fixedly held above the turntable 201 hinder maintenance work which includes replacing the polishing pad 202 attached to the upper surface of the turntable 201 with a new one.
(2) Although it is desired that the liquid discharged from the nozzle 203 falls onto the polishing surface of the turntable 201 at a position suitable for the liquid to be appropriately spread over the polishing surface of the turntable 201 by a centrifugal force, i.e., a position near the center of rotation of the turntable 201, the position on the polishing surface of the turntable 201 where the liquid falls may be different from such a desired position depending on the flow rate and velocity of the discharged liquid.
The present invention has been made in view of those problems and it is therefore an object of the present invention to provide a polishing machine with a liquid supply system that does not hinder maintenance work such as the exchange of polishing pads and is capable of positively supplying a liquid at an optimum position on a polishing surface of a turntable.
According to the present invention, a polishing machine is provided with a liquid supply system comprising a movable arm, and a nozzle supported on the movable arm to supply a liquid onto a polishing surface of a turntable.
The movable arm is movable between a liquid supply position whereby the nozzle is positioned substantially vertically above a portion of the polishing surface onto which the liquid is to be discharged, and at least one retracted position whereby the nozzle is positioned outside the periphery of the turntable. The polishing machine further comprises a holding device for holding the arm at either the liquid supply position or the retracted position.